Molds reproduce using tiny spores that waft through the indoor and outdoor air all the time. Given a damp place to land, mold spores may grow and digest whatever they landed on to survive. Various molds can grow on numerous surfaces, including wood, paper, carpet, and foods. Very moist areas or places where water has accumulated indoors are ideal habitats for mold, especially if the moisture is not discovered or addressed. Although you cannot eliminate all indoor mold and mold spores, you can control its growth by controlling indoor moisture. Descriptions of some common molds are provided below.
Stachybotrys Chartarum (Black Mold)
Stachybotrys usually looks black and slimy. These molds flourish on cellulose-rich materials in the presence of water. Sheetrock, paper, ceiling tiles, insulation backing, and wallpaper are some examples of water-damaged materials on which these molds are frequently found. It needs a long time and quite a lot of moisture to grow. This is why we typically find Stachybotrys indoors when water damage has not been noticed or has been ignored. Stachybotrys produce mycotoxins that are remarkably toxic, suspected carcinogens, and immunosuppressive. These mycotoxins can cause exposure symptoms when inhaled or ingested as well as when on the skin. Signs of exposure include dermatitis, cough, runny nose, nose bleeds, cold- and flu-like symptoms, headache, fatigue, and fever.
In our modern environment, Aspergillus is the most common genus of fungi encountered. The genus includes more than 160 different species. To date, sixteen of them are known to cause human disease. In the United States, Aspergillosis is the second most common fungal infection requiring hospitalization.
Most Aspergillus infections are caused by Aspergillus fumigatus. It easily grows at temperatures up to 55ºC and can be found in abundance in decomposing organic material, such as compost piles that are self-heating. Frequently handling contaminated material without appropriate protective gear can cause you to become hypersensitive to Aspergillus spores. Subsequent exposure may cause severe allergic reactions.
This is the second most encountered cause of Aspergillus infection. Aspergillus flavus produces aflatoxin, an extremely potent carcinogen. In Great Britain, 100,000 young turkeys died from eating contaminated feed in the 1960s. It should be noted that the risks of airborne exposure to Aspergillus flavus have not been sufficiently studied and no exposure standards exist.
Although this is the most commonly found Aspergillus species in nature, it is the third most common cause of disease. It can grow on a plethora of substrates. This fungus may actively proliferate in the human lung to create a fungal ball that does not invade the lung tissue and may or may not cause symptoms.
There are over 30 species in the Cladosporium genus and the most common are C. elatum, C. herbarum, C. sphaerospermum, and C. cladosporioides. These molds have a velvety to powdery texture and are dark green to black on the front and black on the back. Cladosporium are commonly detectable in indoor and outdoor air. Substrates for growth include decaying plants, woody plants, paint, straw, soil, textiles, and fiberglass liners in supply ducts. Exposure to these fungi causes skin lesions, keratitis, nail fungus, sinusitis, asthma, and respiratory infections. A single large exposure to Cladosporium can cause swelling and bronchospasms, and chronic exposure may cause pulmonary emphysema.
Fusarium are typical soil fungi and can be found on a broad variety of plants. They are commonly detected in humidifiers and has been found in water-damaged carpets and other building materials. Humans may be exposed ingestion of contaminated grains or the inhalation of spores. Fusarium spp. are often the cause of eye, skin, and nail infections. In cases of severe exposure, these fungi can cause hemorrhagic syndrome (alimentary toxic aleukia) in humans. It is characterized by nausea, vomiting, diarrhea, dermatitis, and extensive internal bleeding. Several species of Fusarium produce trichothecene toxins that adversely impact the skin as well as the circulatory, alimentary, and nervous systems. Vomitoxin, one such trichothecene, is associated with outbreaks of acute gastrointestinal illness in humans. Zearalenone, another trichothecene produced by Fusarium, has a structure similar to the female sex hormone estrogen and affects the reproductive organs.
The most common species of Penicillium include P. chrysogenum, P. citrinum, P. janthinellum, P. marneffei, and P. purpurogenum. These fungi are usually found in soil, food, cellulose, grains, paint, carpet, wallpaper, interior fiberglass duct insulation, and decaying vegetation. They may cause asthma and allergic inflammation in the inner part of the lungs in susceptible individuals. These fungi have been seen in patients with inflammation of the cornea, ear infections, pneumonia, endocarditis, peritonitis, and urinary tract infections. Infections from Penicillium fungi typically occur in immunosuppressed individuals. For example, P. marneffei typically infects patients in Southeast Asia that have AIDS. Infection is acquired through inhalation and initially causes a pulmonary infection that then spreads to other areas of the body (lymphatic system, liver, spleen, and bones). It is often fatal. P. marneffei infection can present as papules that resemble acne on the face, trunk, and extremities. Penicillium fungi can also produce mycotoxins. For instance, P. verrucosum generates Ochratoxin A, which is nephrotoxic and carcinogenic. Verrucosidin, also produced by this fungus, exhibits neurotoxicity.
When digesting substrates, fungi secrete enzymes to break down complex compounds into simpler ones that the fungi use as nutrition. As nutrients are digested, secondary metabolic byproducts called mycotoxins are produced. When released, they give the fungi a competitive advantage over other microorganisms and fungi. Mycotoxins can also be highly toxic to humans. They can cause cold- and flu-like symptoms, sore throats, headaches, nosebleeds, fatigue, diarrhea, dermatitis, and immune suppression. Some may even be carcinogenic and teratogenic. Molds known to potentially produce these toxins are Acremonium, Alternaria, Aspergillus, Chaetomium, Cladosporium, Fusarium, Penicillium, and Stachybotrys. These molds do not always produce mycotoxins; they have to be in specific environmental conditions to do so. Currently, the exact conditions that promote mycotoxin production are not known. Scientists need to conduct more research on this topic to understand it fully.